aphi2,

I think that there were recent discussions on both these topics in this forum.

The $100 wiring harness (perhaps from Chevy Duty) is excellent if you have a stock set-up (or just modifications for an alternator and/or turn signals).

The universal harness most likely allows for more modifications (additional electrical items) and might have additional fuses.

I did not change my condenser when I switched to 12v (never had a problem). If you are using the stock ignition set-up (with points), you will have to add a ballast resister in the lead from the ignition switch to the coil (or use a 12v coil with the resister built-in).

Good luck,

Tim